[all-commits] [llvm/llvm-project] 0c7e04: [ARM] One-off identity shuffle

[David Green via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 0c7e044a7f62bba3fb43bf9e5fa7f31289d7e216
      https://github.com/llvm/llvm-project/commit/0c7e044a7f62bba3fb43bf9e5fa7f31289d7e216
  Author: David Green <david.green at arm.com>
  Date:   2021-02-08 (Mon, 08 Feb 2021)

  Changed paths:
    M llvm/lib/Target/ARM/ARMISelLowering.cpp
    M llvm/test/CodeGen/Thumb2/mve-float16regloops.ll
    M llvm/test/CodeGen/Thumb2/mve-shuffle.ll
    M llvm/test/CodeGen/Thumb2/mve-vld3.ll
    M llvm/test/CodeGen/Thumb2/mve-vst3.ll
    M llvm/test/CodeGen/Thumb2/mve-vst4.ll

  Log Message:
  -----------
  [ARM] One-off identity shuffle

A One-Off Identity mask is a shuffle that is mostly an identity mask
from as single source but contains a single element out-of-place, either
from a different vector or from another position in the same vector. As
opposed to lowering this via a ARMISD::BUILD_VECTOR we can generate an
extract/insert pair directly. Under ARM with individually accessible
lane elements this often becomes a simple lane move.

This also alters the LowerVECTOR_SHUFFLEUsingMovs code to use v4f32 (not
v4i32), a more natural type for lane moves.

Differential Revision: https://reviews.llvm.org/D95551